Fluorescent nitrogen-rich carbon nanodots with an unexpected β-C₃N₄nanocrystalline structure

Abstract

We report on nitrogen-doped carbon dots having a β-C3N4crystalline structure and yielding bright tunable fluorescence.

Carbon Dots Dispersed on Graphene/SiO2/Si: A Morphological Study

“…Indeed, this band is consistent with previous data collected from CDs in solution . Absorption and emission spectra with excitation wavelength 530 nm have been recorded for CDs solutions of ethanol and water (see supplementary information) . An absorption band at about 400 nm can be singled out in both solutions.…”

“…Furthermore, the intensity ratio I 2D /I G >2 and the symmetric shape of 2D peak with a full width at half maximum in the range 30–36 cm −1 are typical of single layer graphene (Figure S1, Supporting Information). The Raman spectra of the CDs/Gr systems deposited on SiO 2 (Figure a and b) showed the graphene peaks superimposed to a large photoluminescence band centered at ≈1500 cm −1 (2.15 eV) evidently due to the presence of the CDs. Indeed, this band is consistent with previous data collected from CDs in solution .…”

“…The Raman spectra of the CDs/Gr systems deposited on SiO 2 (Figure a and b) showed the graphene peaks superimposed to a large photoluminescence band centered at ≈1500 cm −1 (2.15 eV) evidently due to the presence of the CDs. Indeed, this band is consistent with previous data collected from CDs in solution . Absorption and emission spectra with excitation wavelength 530 nm have been recorded for CDs solutions of ethanol and water (see supplementary information) .…”

“…CDs were synthesized using citric acid monohydrate (3g) as carbon precursor, and urea (3g) (Sigma–Aldrich) as nitrogen precursor, both dissolved in an aqueous solution (10 mL of Milli‐Q water). The carbonization process was performed exposing the solution to microwave irradiation until the complete evaporation of water occurred . The carbonization produces CDs with average size of 3 nm, crystalline core structures, and surface‐functionalized with amide and carboxylic groups.…”

The origin of emissive states of carbon nanoparticles derived from ensemble-averaged and single-molecular studies

“…Fluorescent H-aggregates allow rather broad variation of intermolecular configurations 71 , up to formation of fiber-like structures 72 . Also, formation of H-aggregated shell hosting a variety of polar functional groups should not be structurally restricted in the case of CDs with amorphous core 75 and the core of nanodiamond structure 50a or core nanocrystal formed by beta carbon nitride groups 76 . The H-type aggregates are formed by side-to-side stacking of chromophores that results in splitting the excited-state energy level (Ee) into two levels.…”